Carrier 58MVP Installation, Start-up, And Operating Instructions Manual

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Carrier 58MVP Installation, Start-up, And Operating Instructions Manual Manual pdf 33 page image

reduction in speed in low heat is to optimize combustion formaximum efficiency.7. Blower on delay—The blower starts 60 sec after flame senseif cycle started in low heat or 35 sec after flame sense if cyclestarted in high heat.NOTE: The blower starts at approximately 400-500 RPM. After20 sec, the motor is turned off for 1/10 of a sec where a coast downcalibration is done to evaluate resistance of the conditioned airduct system. The microprocessor then determines blower RPMrequired to provide proper airflow for heating mode.8. Electronic Air Cleaner—The EAC-1 terminal is energizedwhenever the blower operates.9. Blower off delay—When thermostat is satisfied, the R-W/W1signal is terminated, de-energizing gas valve (stopping gasflow to burners), and HUM terminal is de-energized.The blower reduces its speed to low-heat RPM. The blowerand EAC remain operating 90, 135, 180, or 225 sec (depend-ing on blower off time selection). The furnace is factory set fora 90-sec blower off delay.10. Post purge—The inducer continues operating for 15 sec aftergas valve is de-energized.Step 3—Heating Mode—Two StageThe control center provides 2-stage heating using a single-stagethermostat. The control center maximizes comfort while optimiz-ing efficiency to meet the demands of conditioned area when athermostat R-W/W1 signal is received.If thermostat control over furnace staging is desired, a 2-stagethermostat can be used. When control center receives a thermostatR-W/W1 and R-W2 signal, high heat is energized and when aR-W/W1 signal alone is received, low heat is energized. Thismethod overrides microprocessor control of high or low heat.NOTE: When using 2-stage thermostat operation with R-W/W1and R-W2 signals, setup switch SW-2 MUST be in ON position.The heat cycle operates as stated in Heating Mode section.To allow for greater comfort, 2-stage thermostat control is recom-mended when zone systems are used.Step 4—Emergency Heat ModeNOTE: The furnace should not be operated in emergency heatmode for extended periods of time. Operation is only recom-mended to provide heat until replacement components can beobtained or fault resolved.In this mode, the microprocessor is bypassed and motors operate atfull speed with high-heat operation. The heat exchangers, motors,and electronics can be overstressed and may reduce the life ofcomponents if operated for an extended period.NOTE: No safeties are bypassed when using emergency heatmode.Emergency heat mode can be selected using setup switch SW-4.SW-4 should be used when a fault condition exists or difficult toresolve problems occur. This allows heating until fault can becorrected.In emergency heat mode, the normal heat mode outlined inHeating Mode section is not followed. The following sequencewill occur:When thermostat calls for heat, the R-W/W-1 circuits close.1. Prepurge period—The inducer motor is turned on IMMEDI-ATELY operating at maximum speed, closing low- andhigh-pressure switches. Prepurge begins 25 sec after high-pressure switch closes.2. Blower on—The blower motor is turned on IMMEDIATELYand slowly increases to maximum speed as soon as a call forheat is received. No blower calibration occurs.3. Electronic Air Cleaner—The EAC-1 terminal does notoperate in emergency heat mode.4. Humidifier—The HUM terminal is energized IMMEDI-ATELY.5. Ignitor warm up—The HSI is energized for a 17 secwarm-up period after prepurge period is completed.6. Ignition sequence—After HSI warm-up period has com-pleted, the gas valve is energized, permitting gas flow toburners where it is ignited. After 5 sec, the HSI is de-energized, and a 2-sec flame-sensing period begins.NOTE: Emergency heat mode only operates in high heat.7. Flame sensing—When burner flame is sensed, control centerholds gas valve open. If burner flame is not sensed, controlcenter de-energizes gas valve and ignition sequence is re-peated.NOTE: Ignition sequence repeats 3 additional times before lock-out occurs. Lockout automatically resets after 3 hr, or can bemanually reset by turning 115-v or 24-v power off (not atthermostat) for 3 sec minimum, then turning on again. Fault codeswill not flash in emergency heat mode.8. Blower off delay—When thermostat is satisfied, the R-W/W1signal is terminated, de-energizing gas valve (stopping gasflow to burners), and HUM terminal is de-energized. Theblower stops immediately.9. Post purge—Post purge does NOT occur. The inducer stopsimmediately.Step 5—Cooling ModeSINGLE-SPEED APPLICATIONSWhen thermostat calls for cooling, the R-G and R-Y/Y2 circuitsclose.1. Cooling unit—The cooling unit starts when thermostat R-Ysignal is received.2. Blower on—The control center starts blower immediatelywhen it receives an R-Y/Y2 and R-G signal. The blower startsat approximately 400-500 RPM. After 20 sec, the blower isturned off for 1/10 of a sec where a coast down calibration isdone to evaluate resistance of the conditioned air duct system.The microprocessor then determines blower RPM required toprovide selected cooling airflow.NOTE: In cooling mode, the microprocessor adjusts blower RPMto operate at 400 CFM per ton as selected on A/C setup switches.Airflow will be reduced to 340 or 315 CFM per ton (depending onboard style See Fig. 27) when a dehumidification demand exists.See Air Conditioning Setup Switches section. There is also a charton wiring diagram. (See Fig. 24.)NOTE: If Y/Y2 thermostat lead is not connected to furnacecontrol center, blower motor operates in continuous fan speed andindoor coil freeze-up may occur.3. Electronic Air Cleaner—The EAC-1 terminal is energizedwhenever blower operates.4. Cooling unit—The cooling unit stops when thermostat R-Ysignal is terminated.5. Blower off delay—When thermostat is satisfied, the R-Y/Y2and R-G signals are terminated, and blower remains operatingfor 90 sec. On newer style control boards (See Fig. 27) theblower airflow will drop by 21 percent during the off-delayperiod when the DE jumper is connected. The DE jumper isonly removed to enable the DEHUM input for use with a33→→